I've been going through a lot of MCQ papers recently and they all seem challenging; especially physics. Do you have some tips as to how I can work on MCQ's and anything else that I'm supposed to know? What are some of the common mistakes made by candidates? (Tips and for any of the subjects mentioned below are welcome!)

(I've selected Biology, chemistry, and physics)

(I've been doing MCQ's in chemistry and I've only gotten D's. I'm getting B's in Biology and Physics MCQ's now.)